A technique of estimating the mental state of a user, such as a degree of attention or a degree of concentration, by using information about a gaze or cerebral function of the user and operating an external instrument such as an automobile or a wheelchair has been suggested.
For example, PTL 1 discloses a driver state determining device that can more specifically determine the state of a driver by classifying the state of a driver by three factors including a degree of arousal, a degree of attention and concentration, and a driving ability; detecting at least two pieces of driver information reflecting the respective factors; and determining the state of the driver based on a combination of the detected driver information.
Furthermore, PTL 2 discloses a technique of measuring the distribution of a user's α-wave intensity (cerebral activity fluctuation amount) in the cephalic region and measuring a gaze, and measuring an attention area in the visual field of the user based on the distribution of α-wave intensity and the gaze. PTL 2 also discloses a technique of measuring a pattern of change in the user's α-wave intensity, measuring a degree of attention of the user based on the pattern of change in the α-wave intensity, and controlling the operation of an electric wheelchair according to the measured attention area in the visual field of the user and the measured degree of attention.